"That is really all that's the matter with me."
When word had come to Sokka and his sister about their father, in the midst of the confusion that follows war and proceeds peace, Aang hadn't been there. Those final days of war had caused him to realize how important Guru Pathik's words were, so Aang had decided to get more of them before they became unavailable. Besides, something told him words of wisdom would be scarce during the reconstruction period. He only planned to be gone for a month, but time had stretched until it started to lose meaning when he was with the guru. So when he returned he felt just as he had when he first awoke from that hundred years of slumber: like he had missed the events of a lifetime.
The man (just barely a man, but Aang had trouble believing it) in front of him was just like and yet so unlike the Sokka who had disbelieved he could be beaten by fan-wielding girls, the Sokka who had cried over the loss of his boomerang, the Sokka who had seen through Jet even when Aang had trusted him and the Sokka who had discovered the solar eclipse that Aang wanted to stare. Sokka's new responsibilities had made his stiffer, but there was something else. He listened attentively to Sokka's words, hoping to catch it.
"We heard a few days after you left." Sokka paused to detach himself; he had to move away. "We started to make plans, arranging the ships—all that. I was supposed to be here."
"Why didn't you leave?" Aang gently prodded. He felt Sokka's anguish as he gathered his next words. Aang knew that this was it: the something else.
"Katara got sick, really sick." Sokka puffed out a long breath that turned white in the frosty air. Stars twinkled above him and Sokka lowered his voice as if his words disturbed them. "Iroh was really generous, no diplomatic formalities. That woman who taught Katara some healing stuff from the Northen tribe? The one who knew Gran-gran? I can't—I can't remember her name. She came. Doctors from every nation." Sokka shook his head and kicked the crusty snow with the toe of his boot. Then he looked plaintively at his friend. "Aang, I thought she was going to die."
"But she didn't." Aang had already seen Katara, already knew the outcome of Sokka's story, but he still had to hear Sokka confirm it.
"No, she didn't." Sokka tucked his arms behind his back and looked towards the sea from his newly built watch tower. A very small smile formed on his lips. "She didn't die because she wouldn't." And then the something else was gone. Sokka turned back towards Aang to ask jovially "What have you been doing all this time?" Aang answered with a casualness he didn't feel and the conversation flowed on, only now he thought he understood the rigidness pervading the young chieftain's stride and why Katara, who was as sweet and as compassionate as always, was quieter.